Qdevice for Non-HA cluster?


Renowned Member
Jul 28, 2015
So I'm pretty sure I know the answer. I'm building a very small cluster for now. Two nodes. One hosts the NAS and SAN and a few other 'infrastrcture-y' things. The other hosts most of the VMs that I want to boot *from* the SAN. I can manually migrate them from the service node to the infra node if I need to, say, to avoid interrupting a project during an update. I'm generally not worried about anything on the service node failing spontaneously if there's a system restart, and since it's clustered with network storage, I can bring it back up on the infra node if I need it. All that being the case, if I'm not doing anything overtly dumb like trying to join a third new machine to the cluster with a split brain, or running ceph, or the like, do I really care about quorum for the day-to-day operation? If one goes down, *can* I actually manually bring up a Non-HA VM on the other node without quorum? Reliability isn't a concern. I have a cold spare server, and could have a *dead* server replaced in a few hours in most cases, and a few days if I need spare parts (I'm also building up the spare part stockpile where applicable, slowly).

TL;DR: If I'm not using HA in a two-node cluster, how important is Quorum, and can a single node in the cluster continue to function semi-sanely without Quorum?

If one goes down, *can* I actually manually bring up a Non-HA VM on the other node without quorum?
no, when the cluster is not quorate, you cannot do anything to change the state... (starting/stopping/modifying config/etc.) without manual intervention (you could set the 'expected votes' but that is not recommended because it just forces the remaining nodes to be quorate)

running vms, etc will continue to run though
in any case i'd recommend running a (small) third node as qdevice


The Proxmox community has been around for many years and offers help and support for Proxmox VE, Proxmox Backup Server, and Proxmox Mail Gateway.
We think our community is one of the best thanks to people like you!

Get your subscription!

The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get yours easily in our online shop.

Buy now!